Nesfatin-1 is a hormone and a naturally occurring protein molecule produced by the brain of mammals. Japanese scientists discovered in 2006 that it is responsible for regulating appetite and production of body fat.[1] Excess nesfatin-1 in the brain leads to a loss of appetite, less frequent hunger, a 'sense of fullness', and a drop in body fat and weight. A lack of nesfatin-1 in the brain leads to an increase of appetite, more frequent episodes of hunger, an increase of body fat and weight, and the inability to 'feel full.' This latter condition can be artificially induced by injecting an anti-nesfatin-1 antibody into the brain. The receptors within the brain are not completely understood, although they are thought to be contained in the hypothalamus and in the solitary nucleus, where nesfatin-1 is believed to produced via peroxisome proliferator-activated receptors (PPARs).

Through observation, it appears there is also some unknown relationship between nesfatin-1 and cannaboid receptors. However its precise mechanism and effect remain controversial. Discovery and study of nesfatin-1 was assisted by Hiroyuki Shimizu at Gunma University Graduate School of Medicine within the Medicine and Molecular Science department with assistance by research conducted at Saitama University (Saitama,
Japan) and the Nippon Medical College (Tokyo, Japan).